King Palms, Throatworts, & Sunflowers

It was nearly 20 years ago that I paid my first visit to the Virginia Robinson Gardens in Beverly Hills. Many of the plants that I saw on that visit have disappeared but the Iochromas remain.
Iochroma cyathea is a memorable plant with clusters of violet to purple tubular flowers hanging down like a conglomeration of bell clappers. Iochromas seem to be in bloom most of the time and are attractive to hummingbirds. Silver sage (Salvia argentea) is another distinctive perennial on display at Virginia Robinson Gardens. Silver sage is indigenous to southern Europe, from Portugal to Bulgaria. Its cabbage leaves are covered with a silvery fur, an insulating feature that imparts considerable drought tolerance.
Throatwort (Trachelium caeruleum) is another favorite in the Gardens, coming from southwest Europe, a habitat shared by an iridescent yellow rockrose (Halimium lasianthum). Throatwort has foamy wine-colored flower heads that match up well with burgundy-tinged metallic foliage, and the delicate yellow rockrose has a dark, blood-red crown at the base of each flower petal.
The Gardens also show off a number of provocative Sedum nussbaumerianum, a succulent with distinctive yellow-orange foliage. Nussbaum’s sedum provides a colorful foliar contrast in beds of drought-tolerant species, whether succulent or leafy, whose foliage is typically dull green, gray, silver or chalky blue.
The outstanding feature of the Gardens is a naturalizing king palm grove. In botanical jargon, to naturalize means to drop seeds that produce viable seedlings in place. King palm (Archotophoenix cunninghamii) is native to tropical Australia. I learned from Tim Lindsay, superintendent of the Gardens, that the king palm grove in Beverly Hills is the only such grove in North America where the trees have naturalized.
Virginia Robinson Gardens is open to the public by appointment. You can arrange for a tour by calling 310-550-2065, or by email at visit@robinsongardens.org.
Tip of the week
At Virginia Robinson Gardens, I was surprised to learn that hybrid lilies can last for years in Southern California gardens, contradicting my own one-and-done experience with them. I was told that a scarlet-red hybrid I noticed had come back each of the last six years. I could not help wondering if the specimens I saw were one of the recently created LA hybrids. LA hybrids (not having to do with the city, ironically enough, but indicating a longiflorum x Asiatic lily hybrid) are highly recommended for this part of the world.
SUNFLOWERS 101
Reader Steve Ledoux wrote to tell me about some ‘Mammoth’ sunflower (Helianthus annuus) seeds he planted in his mother-in-law’s yard in Northridge. Only one seed developed into a full-fledged plant and now his mother-in-law, Irene Becktold, together with her circle of friends, have some questions they would like me to answer.
Let’s take them one by one:
How long can a sunflower last?
Attached to the mother plant, an individual sunflower lasts from two to four weeks before it fades. But any given plant may produce sunflowers throughout the growing season, from spring into late summer.
If you detach a sunflower for a vase arrangement, cut the stem at an angle and place it in a tall vase. Before placing the stem in water, make sure to remove all leaves that would be submerged. Leaves under water, on any cut flower stem, are likely to be smitten with water mold that shortens the life of the flower above. The sunflower’s greatest enemy is desiccation so make sure you place it in a tall vase full of water.
On a daily basis, cut off a small piece at the bottom of the stem, always at an angle, to extend the life of your sunflower. Add a floral preservative for good measure.
Is there a way to keep squirrels from stealing the flowers?
The best squirrel deterrent is a pet cat and, secondarily, a pet dog.
If you are petless, consider placing squirrel deterrent substances around your sunflower plants. There is anecdotal evidence that mothballs, peppermint oil, coffee grounds and cayenne pepper have a deterrent effect on squirrels, as does the ammonia in used cat litter.
Black plastic mesh is also recommended for covering the emerging plants as a shield. Once the plants have matured, cover each sunflower in a paper bag to fend off squirrels and birds, until the seeds are ready to harvest.
What varieties of sunflowers are typically used for the seeds we eat?
Although endemic to the Great Plains, the sunflowers most commonly grown for their edible seeds were hybridized in Russia, whose steppes mimic the Great Plains in terms of soil and climatic conditions.
The most common edible varieties are ‘Mammoth’ or ‘Mammoth Russian.’ ‘Russian Giant,’ ‘Kong,’ ‘Giganteus,’ ‘Jumbo,’ ‘Giant Grey Stripe’ and ‘Paul Bunyan Hybrid’ are other popular edible varieties.
Dozens of sunflower varieties exist, including ornamentals in many versions of yellow and orange, as well as red- and bronze-colored types and dwarfing varieties that are only 2 to 4 feet tall.
What variety of sunflowers did Vincent Van Gogh paint?
Sunflowers arrived in Europe via Spain and its returning explorers who first reached the Great Plains in the 1540s. In the 1880s, Van Gogh was painting them in Arles, France. Most of the sunflowers on Van Gogh’s canvases are a mutant double-flowered type. Their pompom heads resemble chrysanthemums, which are sunflower cousins.
You can purchase seed packets of ‘Sungold,’ a double-flowered variety that could have stood in a vase in Van Gogh’s studio, for $1.99 (plus shipping) through www.swallowtail gardenseeds.com.
What other flowers can grow as tall as sunflowers?
Tree dahlias (Dahlia imperialis), which are sunflowers’ botanical kin, can grow up to 20 feet tall. Their flowers are lavender pink. Tree dahlias are perennials that are cut back to ground level on an annual basis. This means that a plant may put on as much as 20 feet of growth in a single season.

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About The Author

Welcome to The Smarter Gardener. I'm Joshua Siskin and I've been writing about plants and trees for the Los Angeles Daily News for over 20 years. If you have any questions or comments, please send them along. I have published more than 1,000 articles on plants and I am currently in the process of loading them onto this site. My goal is to make it possible for you to learn about any of the plants in your garden by doing a search of this site.